1
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Let $$\overrightarrow \alpha $$ = $$\widehat i + \widehat j + \widehat k$$, $$\overrightarrow \beta $$ = $$\widehat i - \widehat j - \widehat k$$ and $${\overrightarrow \gamma }$$ = $$ - \widehat i - \widehat j - \widehat k$$ be three vectors. A vector $$\overrightarrow \delta $$, in the plane of $$\overrightarrow \alpha $$ and $$\overrightarrow \beta $$, whose projection on $${\overrightarrow \gamma }$$ is $${1 \over {\sqrt 3 }}$$, is given by
A
$$ - \widehat i - 3\widehat j - 3\widehat k$$
B
$$\widehat i - 3\widehat j - 3\widehat k$$
C
$$ - \widehat i + 3\widehat j + 3\widehat k$$
D
$$\widehat i + 3\widehat j - 3\widehat k$$
2
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Let $$\overrightarrow \alpha $$, $${\overrightarrow \beta }$$, $${\overrightarrow \gamma }$$ be the three unit vectors such that $$\overrightarrow \alpha .\overrightarrow \beta = \overrightarrow \alpha .\overrightarrow \gamma = 0$$ and the angle between $$\overrightarrow \beta $$ and $$\overrightarrow \gamma $$ is 30$$^\circ$$. Then $$\overrightarrow \alpha $$ is
A
2($$\overrightarrow \beta $$ $$ \times $$ $$\overrightarrow \gamma $$)
B
$$-$$ 2($$\overrightarrow \beta $$ $$ \times $$ $$\overrightarrow \gamma $$)
C
$$ \pm $$ 2($$\overrightarrow \beta $$ $$ \times $$ $$\overrightarrow \gamma $$)
D
($$\overrightarrow \beta $$ $$ \times $$ $$\overrightarrow \gamma $$)
3
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
For any vector x, where $$\widehat i$$, $$\widehat j$$, $$\widehat k$$ have their usual meanings the value of $${(x \times \widehat i)^2} + {(x \times \widehat j)^2} + {(x \times \widehat k)^2}$$ where $$\widehat i$$, $$\widehat j$$, $$\widehat k$$ have their usual meanings, is equal to
A
$$|x{|^2}$$
B
2$$|x{|^2}$$
C
3$$|x{|^2}$$
D
4$$|x{|^2}$$
4
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
If the sum of two unit vectors is a unit vector, then the magnitude of their difference is
A
$$\sqrt 2 $$ units
B
2 units
C
$$\sqrt 3 $$ units
D
$$\sqrt 5 $$ units
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